1. Field of the Invention
This invention relates generally to orthopaedic instrumentation and, more particularly, to orthopaedic cutting instruments.
2. Related Art
Most orthopedic instruments rely on bone spikes or pins for fixation. Other instruments use an intramedullary (IM) instrument with coupling configurations for the purpose of instrument correlation. However, these previous devices do not control all degrees of freedom. These previous devices are not stable nor are they relatively accessible.
Other instruments connect to a preset-length, intramedullary instrument through a threaded connection. This method restricts the amount of stability achieved to what is derived from the preset-length intramedullary instruments. If it were possible not to restrict the intramedullary instrument length, a surgeon could first stabilize the intramedullary instrument and then rigidly connect the correlating instrument to the intramedullary instrument.
Typically, the intramedullary or axial reference instrument(s) and/or the guide assembly are removed before resection because absent such removal the guide or instrument would interfere with the resection. Thus, the stability gained through the connection of the guide assembly and the axial reference instrument is typically lost.
The cutting plane and/or axis must be derived anatomically, usually through intramedullary referencing. However, in some instances, an alternative reference axis is utilized for unusual circumstances (i.e., deformities, trauma, disease, etc.). In either case, an instrument establishing a reference axis usually relative to a mechanical axis (i.e. intramedullary referencing) is rigidly fixed to/in bone. A cutting guide, with or without a guide assembly, is attached to this reference axis with a purpose of deriving a cutting plane and/or axis (i.e., posterior slope, valgus angle, etc.). The cutting guide is usually fixed to the bone using a bone spike(s), screw(s), drill(s) and/or pin(s). Normally, the reference axis and guide assembly are then removed for clearance for a cutting instrument.
There remains a need in the art for a device that can accurately establish rigid fixation of an instrument relative to an intramedullary reference axis. Further, there remains a need in the art for a modular device that allows for positioning of cutting guides and alignment guides relative to an intramedullary reference axis.